Another small bug fix and added validate_itf14, fix_itf14_checksum.
Another small bug fix and added validate_itf14, fix_itf14_checksum.

zahiruldu/UPC-A-EAN-13-Maker,GameMaker2k/UPC-A-EAN-13-Maker,GameMaker2k/UPC-A-EAN-13-Maker,zahiruldu/UPC-A-EAN-13-Maker